The present invention relates to a polarizer for separating two linearly polarized electromagnetic waves and including a tubular element to which are connected two wave guides having different dimensions in a plane transverse to the direction of wave propagation, and wherein one of the wave guides is connected to the tubular element so that the front end of the former joins laterally the latter.
Polarizers of the type to which the invention pertains are, for example, needed for running differently polarized electromagnetic waves to and/or from directional antennas in radio links or the like. Whereby, for example, one path is provided for transmission purposes, the other one for receiving. Basically it is possible to run the two waves separately, i.e. through two separate wave guide or wave guide systems between the antenna and the transmitter and the receiving circuitry placed elsewhere. If the distance to be bridged in this manner is large (and that is usually the case) a significant expenditure is necessary. For example, the reflector of an antenna may be placed on top of a high tower, being up to a thousand feet high. Therefore, wave guides have to run up the tower because the electric circuitry is, of course, at ground level. Long distances do not only occur in the case of a high antenna mast but in other circumstances. Moreover, the ground station may not necessarily be located right at the mast. It has been suggested to conduct two waves which are vertically or transversely polarized with respect to each other in a single wave guide with round or square-shaped cross section. At one end of the single wave guide, the two waves are combined and at the other end then are separated. For this purpose, one needs a polarizer which permits low reflection feeding and extraction of the waves.